refactor into modules

src/bin/experiment.rs

@@ -1,10 +1,11 @@
-use image_similarity::descriptors::{Descriptor, Median};
+use image_similarity::descriptors;
+use image_similarity::descriptors::Descriptor;
 use std::collections::HashMap;
 use std::fs;
 
 fn main() {
     //Init all descriptors:
-    let desc = Median;
+    let desc = descriptors::dct::DCT::new();
 
     //Initialize hashmap, empty or from cached file:
     let count = fs::read_dir("img").unwrap().count();